A. Technical Field
The present invention relates to a microgyroscope for determining rotational motions about at least one of three perpendicular spatial axes x, y, and/or z, having a substrate on which multiple masses which oscillate parallel to the plane of the substrate in an x-y plane are situated, some of the oscillating masses being attached to the substrate by means of springs and anchorings, having drive elements for maintaining oscillating vibrations of the masses which are subjected to Coriolis forces when the substrate rotates about any given spatial axis, and having sensor elements for detecting the deflections of the masses due to the Coriolis forces generated.
Microgyroscopes are generally used for determining a rotational motion about an axis in an orthogonal x-y-z coordinate system. Therefore, three such microgyroscopes are necessary to be able to determine rotational motions of the system about each of the three axes. This entails high expense, and complicated control and evaluation of the data.
B. Background of the Invention
A triaxial microelectromechanical (MEMS) gyroscope is known from TW 286201 BB. Masses which are situated on a central anchoring are set in oscillating rotational motion. The masses are arranged on a substrate, and when there is a torque about the x or y axis the masses are tilted about the y or x axis, respectively, due to a Coriolis force which occurs. This is made possible by an appropriate suspension of these drive masses on the substrate. When there is a torque about the z axis, partial masses are translationally deflectable by an appropriate suspension of these partial masses on the rotatably supported masses. The tilting motions as well as the translational motion may be detected by sensors, and due to their proportionality to the rotational motion of the substrate, are used as a measure of the corresponding rotation about the x, y, or z axis. However, the respective deflections are very difficult to determine.
To allow a three-dimensional gyroscope to be provided for which rotations about all three axes may be determined, in the 1996 article titled “A monolithic silicon gyroscope capable of sensing about three axes simultaneously,” D. Wood et al. proposed a gyroscope having oscillating masses annularly arranged around a central anchoring. These masses are able to undergo tilting motions as well as rotational motions as the result of Coriolis forces which occur. It is disadvantageous that it is difficult to manufacture such a sensor and to drive the moved masses. The motions of the individual components of the sensor have a mutual influence on one another, so that measurements of the motion in the x, y, or z direction of the gyroscope do not provide sufficient accuracy.
One-dimensional and two-dimensional gyroscopes are also basically known which are able to detect tilting and rotational motions of the gyroscope only about one or about two of the three spatial axes x, y, and z. Fairly simple gyroscopes of this type are adequate for many applications.